Problem: Constraints

* H is an integer between 2 and 50 (inclusive).
* W is an integer between 2 and 50 (inclusive).
* s_{i, j} is `.` or `#` (1 \leq i \leq H, 1 \leq j \leq W).
* s_{1, 1} and s_{H, W} are `.`.

Input

Input is given from Standard Input in the following format:


H W
s_{1, 1}s_{1, 2}s_{1, 3} ... s_{1, W}
s_{2, 1}s_{2, 2}s_{2, 3} ... s_{2, W}
:   :
s_{H, 1}s_{H, 2}s_{H, 3} ... s_{H, W}


Output

Print the maximum possible score that Snuke can achieve, or print -1 if the game cannot be completed.

Examples

Input

3 3
..#
#..
...


Output

2


Input

3 3
..#
..
...


Output

2


Input

10 37
.....................................
...#...####...####..###...###...###..
..#.#..#...#.##....#...#.#...#.#...#.
..#.#..#...#.#.....#...#.#...#.#...#.
.#...#.#..##.#.....#...#.#.###.#.###.
.#####.####..#.....#...#..##....##...
.#...#.#...#.#.....#...#.#...#.#...#.
.#...#.#...#.##....#...#.#...#.#...#.
.#...#.####...####..###...###...###..
.....................................


Output

209

Solution (in PYTHON3):

Solution:
h,w=map(int,input().split())

field=[list(input())for i in range(h)]
cnt=0
for i in field:
    for j in i:
        if j=='#':
            cnt+=1
dp=[[0 for i in range(w)]for i in range(h)]

dydx=[[-1,0],[1,0],[0,-1],[0,1]]

queue=[]
queue.append([0,0])

while queue:
    ny,nx=queue.pop(0)
    for dy,dx in dydx:
        nny,nnx=ny+dy,nx+dx
        if 0<=nny<=h-1 and 0<=nnx<=w-1 and field[nny][nnx]!="#" and dp[nny][nnx]==0:
            dp[nny][nnx]=dp[ny][nx]+1
            queue.append([nny,nnx])
            if nny==h-1 and nnx==w-1:
                print(h*w-cnt-dp[h-1][w-1]-1)
                exit()
print(-1)